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Is there a Catch in Eating Tuna?

Posted by Lisa Peterson -

How important is fish in the diet? Is canned tuna in water healthier than in oil? Isn't the mercury harmful? These three questions have come up in conversation during heart health classes over the last few weeks. The American Heart Association recommends eating fish two times a week. The 2015-2020 Dietary Guidelines for Americans recommend 8 ounces of a variety of seafood per week for both the general population and women who are pregnant or breastfeeding, averaging 250 milligrams of Omega 3 fatty acids DHA and EPA. In following with the dietary guidelines, research shows individuals who consume eight ounces of seafood per week are at a reduced risk a cardiac event, with or without a pre-existing condition. One inexpensive fish readily available is tuna. Canned tuna is the second most popular seafood in the United States behind shrimp. Aside from the Omega-3 fatty acids, tuna is also a good source of nutrients such as B vitamins, vitamin D, selenium and additional vitamins and minerals.

What's so special about Omega-3 Fatty Acids?

Omega-3 fatty acids or essential fats, are a type of polyunsaturated fat that the body needs but must be consumed through food. DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) are two types of omega-3 fatty acids found in every cell membrane in the human body. Both nutrients assist in gene expression, communication between cells, flexibility, help in cell metabolism, and as a lubricant.Omega-3 fatty acids are especially important for pregnant women, as the DHA consumed by the mother helps with brain and eye development for the baby. Just because the body cannot make omega-3 fatty acids, doesn't mean they are not needed. Research shows Omega-3 fatty acids can help reduce blood clotting in the arteries, and delay the onset of atherosclerosis; lowers blood pressure, prevents an irregular heartbeat, reduce inflammation, and in high doses can reduce triglyceride levels. Aside from oily fish such as tuna, salmon, and sardines, omega-3 fatty acids are also found in chia seeds, kale, flaxseed, Brussel sprouts, and walnuts.

What about the Mercury?

First, mercury is a heavy metal that occurs naturally and can also be found due to industrial pollution. The mercury that is found in streams, rivers, and oceans is called methyl mercury, and considered harmful in large amounts to unborn babies, infants, and young children. Fish absorb the methyl mercury from the water and it can build up in their body. Almost all fish contain traces of methyl mercury, but older and larger fish tend to accumulate more. See the chart below for foods high and foods low in mercury. Young children and pregnant women are recommended by the Food and Drug Administration to avoid fish with high levels of mercury as the mercury can interfere with nervous system development.

Fish HIGH in Mercury

Fish LOW in Mercury

  • King Mackerel
  • Tilefish
  • Swordfish
  • Shark
  • Shrimp
  • Catfish
  • Pollock
  • Canned Light Tuna
  • Salmon

Overall, the FDA advises eating no more than 12 ounces a week of fish and shellfish low in mercury, such as the fish listed above. Albacore (white tuna) contains more mercury than canned light tuna, but three times as much omega-3 fatty acids. Light tuna is skipjack, yellowfin, tongol, and sometimes big eye tuna. Canned light tuna may be a combination of different species. Incorporate fish and shellfish twice a week, and only half (6 oz.) from the albacore or steak tuna per week.

Oil vs. Water Packed Tuna

One readily available and inexpensive source of omega 3 fatty acids is canned or vacuum packaged tuna. Canned tuna is available in water or oil. Tuna packaged in water is lower in fat and calories, but has a similar amount of sodium, cholesterol, and protein as oil packed. Although tuna packaged in water is lower in calories, tuna in oil is packed in heart healthy fats such as olive oil or soybean oil. Read the nutrition labels, tuna packaged in water retain a higher level of EPA and DHA. Water and oil do not mix, meaning when draining water packed tuna the oils stay with the tuna and the essential fatty acids do not go down the drain. Individuals may prefer one over the other based on texture or flavor. Tuna canned in oil is also cooked in oil and has a stronger fish taste.

Canned vs. Vacuum Packed (Pouch) Tuna

Both canned and vacuum packed tuna, also called pouch tuna, should be stored at room temperature in a cool and dry place. Pouch tuna is stored without water, has a chunkier texture, and has a stronger tuna flavor. Because of packaging, vacuumed packed tuna is typically more expensive than canned.

Storage & Handling

  • Research shows canned tuna should be consumed within 6 months of purchase for an optimum amount of omega-3 fatty acids
  • Canned or pouch tuna, for optimum quality, should be stored in a cool and dry place, such as a pantry
  • Store recently purchased tuna behind older to help remember to use older products first
  • If cans or pouches are rusted, bulging, torn or dented, do not use them as these are all signs of spoilage. When in doubt, throw it out.
  • The average shelf life of canned tuna is 4 years and vacuumed packaged or pouched tuna is 3 years when kept in optimum conditions. Check the can, package, or manufacturer for best when used by dates. Once opened, store fish in a sealed container in the refrigerator and consume or toss after 3-4 days.

Overall, canned or pouched tuna is a wonderful source of protein and heart healthy essential omega-3 fatty acids. Make a goal of eating fish twice this week or make it a part of two meals. Looking for a new recipe this week with tuna? Try a unique tuna fritter side dish below the whole family will love!

Sweet Tuna Fritters

6 oz. canned light tuna in water, drained

1 egg

2/3 cup rolled quick oats

2 Tbs. barbeque sauce

3 Tbs. chopped green onions

1 tsp. chili powder

1 tsp. Italian seasoning

½ tsp. garlic powder

2 Tbs. olive oil

  1. In a small bowl, beat egg and combine tuna, oats, bbq sauce, onions, chili powder, Italian seasoning, and garlic powder.
  2. Over medium heat, coat pan in 2 tbs. olive oil. Scoop one tablespoon of batter into pan; flip every 3 minutes until a golden brown.

*Hint: To create a spicier fritter add an extra 1/2 -1 tsp. chili powder

Yield: 10 servings (fritters)

Nutrition Facts: 1 serving: 80 calories, 4 g. fat, .5 g. saturated fat,30 mg.cholesterol, 125 mg. sodium, 6 g. carbs,1 g. dietary fiber, 5 g. protein

For republication of this blog post, please contact Lisa Peterson, Nutrition & Wellness Educator, or Terri Miller, publicity & promotion specialist, Thank you!



Asim Maqbool, Birgitta Strandvik and Virginia A Stallings (2011). The skinny on tuna fat: health implications. Public Health Nutrition, 14, pp 2049-2054. doi:10.1017/S1368980010003757.

"About Seafood." National Fisheries Institute.

Siriamornpun S, Lifeng Y, Kubola J, Duo L. CHANGES OF OMEGA-3 FATTY ACID CONTENT AND LIPID COMPOSITION IN CANNED TUNA DURING 12-MONTH STORAGE.Journal Of Food Lipids[serial online]. June 2008;15(2):164-175. Available from: Business Source Complete, Ipswich, MA. Accessed March 22, 2016.

"What you Need to Know about Mercury in Fish and Shellfish." U.S. Food and Drug Administration. March 2004.

"What you Should Know about Tuna." Berkley Wellness. University of California Berkley. 1 October 2011.

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